The present invention relates to the field of hydraulics, more particularly to high pressure poppet valves. This invention provides improved dampening, which results in greater stability in such valves.
Hydraulic systems and controls connected thereto often require valves for relieving fluid from a first passage having a relatively high fluid pressure to a second passage having a relatively low fluid pressure. For instance, a pilot operated pressure regulating system for open circuit pumps requires a high pressure pilot relief valve. Various high pressure relief valve configurations are known in the art of hydraulics.
One configuration, known as a poppet valve, utilizes a poppet that is spring biased into engagement with a seat at the bottom of a valve bore. During operation of the poppet valve, the poppet disengages from the seat or "cracks off" when the pressure on the seat area balances the spring force. The "cracking pressure" of the valve is the pressure at which the poppet cracks off the seat. High velocity fluid then flows adjacent the poppet. As the kinetic energy of the fluid is dissipated in the discharge chamber, a great deal of turbulence is typically generated and the poppet may become unstable as a result. Because of the high pressures and fluid velocities encountered, conventional poppet valves often exhibit unstable performance, rapid wearing of the valve seat and/or poppet, high valve leakage and degradation of the valve seat pressure.
Various measures have been tried to eliminate the shortcomings noted above. Increasing the spring rate of the valve improved stability, but resulted in adjustment problems due to the higher spring rate. Furthermore, the gain or flow/pressure relationship was reduced to an undesirable level. Existing poppet valve designs have also addressed the wear problem by using harder and more exotic materials on the valve seat and/or the poppet. Unfortunately, such measures tended to increase the manufacturing costs for these components.
Therefore, a primary objective of the present invention is the provision of a high pressure relief valve that represents an improvement over existing high pressure relief valves.
Another objective of the present invention is the provision of a poppet-style high pressure relief valve which has excellent repeatability and predictable flow/pressure characteristics.
Another objective of the present invention is the provision of a valve having stable operating characteristics.
Another objective of the present invention is the provision of a valve having low leakage when operating below its cracking pressure.
Another objective of the present invention is the provision of a valve that can be accurately adjusted and has good resolution during adjustment.
A further objective of the present invention is the provision of a valve having a relatively long life with little degradation in terms of the setting or leakage over the life of the valve.
A further objective of the present invention is the provision of a valve that is relatively quiet in use.
A further objective of the present invention is the provision of a valve that is economical to manufacture and durable in use.
These and other objectives will become apparent to one skilled in the art from the description which follows and the accompanying drawings.